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Saw this on another site and thought it was a good read...........
Muscle typing is claimed to be overrated and less important then other factors, but I believe it is of significance for those who have everything dialed in. What I mean is, with all things being equal it is ?usually? advantageous to have a greater preponderance of fast twitch muscle fibers, particularly IIB, because they produce greater peak power and more force at higher velocities. The advantages of a certain fiber composition on performance in various sports is both obvious and well established -- For example, marathon runners have 75% slow twitch fibers while sprinters have 75% fast twitch fiber (both IIA &B combined).
The ratio of your fiber type is a result of:
(1) What you were born with
and
(2) Transformation of slow to fast or fast to slow through training influence.
Transformable Fibers
If you were to look at a muscle biopsy you?d see both red and white along with various shades of each. The white being pure fast twitch and the red being pure slow twitch. Think of eating chicken, the white meat (breast) is fast twitch. The dark meat (legs and thigh) is slow twitch. Chickens don't fly around very often yet when they do those muscles have to fire quicker, thus, their breast meat is fast twitch. Chickens walk around on their feet all day long thus their legs are slow twitch and better suited for endurance.
As mentioned before you can't take a completely red (pure endurance fiber) and turn it into a completely white (fast twitch) fiber but the intermediate fibers (IIA), which would be the various shades you see in a muscle biopsy can be transformed into more of a red (slow twitch) version or more of a white (fast twitch) version. You can also take a pure white fiber and make it a little redder, or take a pure red fiber and make it a little whiter.
Canadian scientists, Drs. J. Simoneau and C. Bouchard, have estimated that 40% of the variance of fiber type is due to environmental influences (i.e. exercise) while 45% is associated with genetic factors. So that means you have about 40% control of your muscle fiber type, the other 45% you can do nothing about.
Real World Application
So how can you use this information and apply it in the real world? Well take someone who is say 50/50 fast vs slow-twitch. Over time and with proper training if he trains his nervous system to utilize 90% of all those available FT fibers and also increases the size of them he well then be able to outperform someone who has say an 80:20 fast to slow-twitch ratio.
In training you can accomplish this by focusing your training on strength, power, and speed dominant activities. By doing so you train your nervous system and all your muscle fibers to behave in more of a fast twitch manner. The reverse can also occur. For example, if one is blessed with a high % of FT fibers and starts marathon training the opposite will occur. I haven't talked much about endurance training but let me mention that it causes a rapid fast to slow transformation (IIb to IIa and IIa to I) without any increases in strength or power, and thus should be minimized by those wishing to maximize speed and power.
Now, for those who really want to zero in on ultra fast twitch muscle conversion there is plenty of ammo out there to use.
First a little background.
Proficiency vs Efficiency
There is a big difference between increased proficiency and increased efficiency. IIB to IIA conversion is more efficient when it comes to meeting metabolic demands. So if the body can get the job done with IIA then it will. Therefore, if you want your body to increase IIB content you need to make sure that the adaptive signals you're sending deem it necessary.
As an athlete you stress your fast twitch fibers a lot. Therefore, your body already perceives that it's a funny car and you're trying to run it on the highway. If your body needs more efficiency what do you think it's gonna do? It's gonna try to find away to make the funny car either run at a low RPM or quit burning up so much gas!! It's gonna make your engine more efficient if it can. How does it do that? One way it does that is by making your fast twitch IIB muscle fibers more endurance oriented.
So how do you get around this and what exactly does send a signal for an increase in IIB?? Well, as mentioned in the earlier article, detraining or "sitting on your butt" is one. With detraining the muscular expression reverts back to its default "fight or flight" readiness. Yet another is hyperthyroidism or overeating.
Complete detraining is not much of an option because you lose more neural efficiency and muscle cross sectional size then can be made up for by any enhanced muscular subtype. Partial detraining and tapering may be an option and I'll get into that one in just a minute. But what about training? Well, if one were to analyze the IIB fiber and MHC IIX expression he could easily come to the conclusion that this fiber type is made for dealing with simultaneous high forces and high speeds.
Some studies show IIa fibers to produce equal force at low velocities compared with IIb, so a rep done under typical strength training conditions (loads only as high as the concentric 1 RM and low velocities) can be adequately handled by IIa. Maybe if the velocity component was increased, and force was maintained or increased, and performed at a volume low enough not to signal the need for more efficiency, we'd see an increase in IIB.
From here one could logically conclude that a training program incorporating movements with a premium on creating a lot of force at high velocities would preferentially induce more expression of these fibers. Thus far, there are a few studies that have looked at this and found this hypothesis to be true. Training methods that duplicate a lot of the tasks seen in gymnasts do exactly this.
Exercises That Increase IIB Expression
These include:
plyometrics utilizing loads, plyometrics, "drop and catch movements", jump squats, olympic lifts, drop jumps, depth jumps, speed squats, speed benches, Reactive squats, as well as most ballistic type activities in which either high speeds, and or supramaximal forces are employed.
The force from a "drop and catch" type movement utilizing loads, or a plyometric type movement, exceeds that which is created with weight training. More importantly, the velocity component and the speed that force must be created is much greater. Put into practice one could start from the top and perform a quick "drop and explode" in a chinup, dip, squat, or olympic lifting movement. The force created at the reversal from eccentric to concentric is great and must be applied extremely quickly or progress will not occur.
Another option would be to simply perform the drop and attempt to stabilize the load towards the bottom as quickly as possible. Yet another option would be to simply de-emphasize the lowering phase of a movement by letting the load come down fairly quickly yet still under control. From here you'd then concentrate on an explosive positive phase. Fred Hatfield stated he used to train like this when he set his world record squat of 1014 lbs. and said it made him 15% stronger.
Short duration heavy isometrics (<10 seconds) in the weakest joint angle of a movement may also be useful to create strength gains without causing negative fast to slow conversions but the jury is still out here. The one thing that should be avoided at all costs is any eccentric movement incorporating loads below 100% of 1rm done at low speeds such as done under typical bodybuilding protocols and/or normal regular paced repetitions. This type of training induces the type of damage that signals the exact adaptations we're trying to avoid. With the aforementioned "high force" methods if the body wants to increase the true "proficiency" of the movement it has no choice but to create a more effective and faster muscle to do it with.
Muscle typing is claimed to be overrated and less important then other factors, but I believe it is of significance for those who have everything dialed in. What I mean is, with all things being equal it is ?usually? advantageous to have a greater preponderance of fast twitch muscle fibers, particularly IIB, because they produce greater peak power and more force at higher velocities. The advantages of a certain fiber composition on performance in various sports is both obvious and well established -- For example, marathon runners have 75% slow twitch fibers while sprinters have 75% fast twitch fiber (both IIA &B combined).
The ratio of your fiber type is a result of:
(1) What you were born with
and
(2) Transformation of slow to fast or fast to slow through training influence.
Transformable Fibers
If you were to look at a muscle biopsy you?d see both red and white along with various shades of each. The white being pure fast twitch and the red being pure slow twitch. Think of eating chicken, the white meat (breast) is fast twitch. The dark meat (legs and thigh) is slow twitch. Chickens don't fly around very often yet when they do those muscles have to fire quicker, thus, their breast meat is fast twitch. Chickens walk around on their feet all day long thus their legs are slow twitch and better suited for endurance.
As mentioned before you can't take a completely red (pure endurance fiber) and turn it into a completely white (fast twitch) fiber but the intermediate fibers (IIA), which would be the various shades you see in a muscle biopsy can be transformed into more of a red (slow twitch) version or more of a white (fast twitch) version. You can also take a pure white fiber and make it a little redder, or take a pure red fiber and make it a little whiter.
Canadian scientists, Drs. J. Simoneau and C. Bouchard, have estimated that 40% of the variance of fiber type is due to environmental influences (i.e. exercise) while 45% is associated with genetic factors. So that means you have about 40% control of your muscle fiber type, the other 45% you can do nothing about.
Real World Application
So how can you use this information and apply it in the real world? Well take someone who is say 50/50 fast vs slow-twitch. Over time and with proper training if he trains his nervous system to utilize 90% of all those available FT fibers and also increases the size of them he well then be able to outperform someone who has say an 80:20 fast to slow-twitch ratio.
In training you can accomplish this by focusing your training on strength, power, and speed dominant activities. By doing so you train your nervous system and all your muscle fibers to behave in more of a fast twitch manner. The reverse can also occur. For example, if one is blessed with a high % of FT fibers and starts marathon training the opposite will occur. I haven't talked much about endurance training but let me mention that it causes a rapid fast to slow transformation (IIb to IIa and IIa to I) without any increases in strength or power, and thus should be minimized by those wishing to maximize speed and power.
Now, for those who really want to zero in on ultra fast twitch muscle conversion there is plenty of ammo out there to use.
First a little background.
Proficiency vs Efficiency
There is a big difference between increased proficiency and increased efficiency. IIB to IIA conversion is more efficient when it comes to meeting metabolic demands. So if the body can get the job done with IIA then it will. Therefore, if you want your body to increase IIB content you need to make sure that the adaptive signals you're sending deem it necessary.
As an athlete you stress your fast twitch fibers a lot. Therefore, your body already perceives that it's a funny car and you're trying to run it on the highway. If your body needs more efficiency what do you think it's gonna do? It's gonna try to find away to make the funny car either run at a low RPM or quit burning up so much gas!! It's gonna make your engine more efficient if it can. How does it do that? One way it does that is by making your fast twitch IIB muscle fibers more endurance oriented.
So how do you get around this and what exactly does send a signal for an increase in IIB?? Well, as mentioned in the earlier article, detraining or "sitting on your butt" is one. With detraining the muscular expression reverts back to its default "fight or flight" readiness. Yet another is hyperthyroidism or overeating.
Complete detraining is not much of an option because you lose more neural efficiency and muscle cross sectional size then can be made up for by any enhanced muscular subtype. Partial detraining and tapering may be an option and I'll get into that one in just a minute. But what about training? Well, if one were to analyze the IIB fiber and MHC IIX expression he could easily come to the conclusion that this fiber type is made for dealing with simultaneous high forces and high speeds.
Some studies show IIa fibers to produce equal force at low velocities compared with IIb, so a rep done under typical strength training conditions (loads only as high as the concentric 1 RM and low velocities) can be adequately handled by IIa. Maybe if the velocity component was increased, and force was maintained or increased, and performed at a volume low enough not to signal the need for more efficiency, we'd see an increase in IIB.
From here one could logically conclude that a training program incorporating movements with a premium on creating a lot of force at high velocities would preferentially induce more expression of these fibers. Thus far, there are a few studies that have looked at this and found this hypothesis to be true. Training methods that duplicate a lot of the tasks seen in gymnasts do exactly this.
Exercises That Increase IIB Expression
These include:
plyometrics utilizing loads, plyometrics, "drop and catch movements", jump squats, olympic lifts, drop jumps, depth jumps, speed squats, speed benches, Reactive squats, as well as most ballistic type activities in which either high speeds, and or supramaximal forces are employed.
The force from a "drop and catch" type movement utilizing loads, or a plyometric type movement, exceeds that which is created with weight training. More importantly, the velocity component and the speed that force must be created is much greater. Put into practice one could start from the top and perform a quick "drop and explode" in a chinup, dip, squat, or olympic lifting movement. The force created at the reversal from eccentric to concentric is great and must be applied extremely quickly or progress will not occur.
Another option would be to simply perform the drop and attempt to stabilize the load towards the bottom as quickly as possible. Yet another option would be to simply de-emphasize the lowering phase of a movement by letting the load come down fairly quickly yet still under control. From here you'd then concentrate on an explosive positive phase. Fred Hatfield stated he used to train like this when he set his world record squat of 1014 lbs. and said it made him 15% stronger.
Short duration heavy isometrics (<10 seconds) in the weakest joint angle of a movement may also be useful to create strength gains without causing negative fast to slow conversions but the jury is still out here. The one thing that should be avoided at all costs is any eccentric movement incorporating loads below 100% of 1rm done at low speeds such as done under typical bodybuilding protocols and/or normal regular paced repetitions. This type of training induces the type of damage that signals the exact adaptations we're trying to avoid. With the aforementioned "high force" methods if the body wants to increase the true "proficiency" of the movement it has no choice but to create a more effective and faster muscle to do it with.